In production and processing activities, machine tools, electrical drills and other tools are often used for boring, milling and other operations. The drill chucks mounted on the working shafts of main engines of such equipment for holding bits, milling cutters and other cutters have been applied and improved for long, but are still observed with various deficiencies. By the source of the force in the drill chuck for pushing the clamping jaw to move up and down inside the clamping jaw hole, drill chucks are mainly classified into the following three types:
The first one is the drill chuck that provides, from outside of the clamping jaw, the force for the clamping jaw to move up and down. Such drill chuck generally has the partial thread outside the clamping jaw. Such thread fits with the thread on the screw nut in the drill chuck jacket. When the drill chuck jacket rotates transversely, the screw nut will be driven to move up and down in the clamping jaw hole.
The second one is the drill chuck that provides, from inside of the clamping jaw, the force for the clamping jaw to move up and down. Such drill chuck generally has the thread inside the clamping jaw. Such thread fits with the thread on drill chuck after-body. When the drill chuck after-body rotates transversely, the clamping jaw will, along with the after-body, move up and down inside the clamping jaw hole.
The third one is the drill chuck that provides, from top of the clamping jaw, the force for the clamping jaw to move up and down. The tops of all the clamping jaws inside this type of drill chuck are fixed to one push block. Through the up-and-down movement of the push block, the clamping jaw moves up and down inside the clamping jaw hole.
The major problem with these types of drill chucks is: when these drill chucks are applied to electrical drills or other tools that rotate and knock in operation, such lasting knocking force will drive the clamping jaw to clamp the cutters continuously and cause an excessive clamping force, thus leaving pits on the cutters and damaging the cutters. In addition, when the drill chuck stops or requires for replacement of cutters, due to the effect of the excessive clamping force generated by the clamping jaw to the cutters under the lasting knocking force, the drill chuck cannot be easily opened, making it much difficult to operate.